DIAGNOSIS CHECKLIST
for Leg rash

Why: to determine if acute or chronic.

Why: diagnosis may be helped when the rash is in a specific area e.g. typical lower leg rashes include keratits pilaris, erythema nodosum, nummular dermatitis, stress dermatitis, necrobiosis lipoidica; typical rashes on the front of the knees include psoriasis and dermatitis herpetiformis; a typical rash on the back of the knees is atopic dermatitis.

Why: i.e. localized to legs or widespread? - If the rash is widespread, is it distributed centrally, peripherally or both.

Why: e.g. may suggest scabies, chicken pox, impetigo.

Why: e.g. atopic dermatitis (eczema), hives, scabies, dermatitis herpetiformis, asteatosis (dry skin). Eczema is usually a chronic and relapsing skin condition.

Why: e.g. soap, frequent washing, chlorinated water, bubbles baths, sweating (because it is drying), sand pits, winter months, extremes of hot and cold weather, emotional stress, wool clothing or blankets, chemical disinfectants, detergents, scratching or rubbing, pregnancy, menstruation, various food stuffs.

Why: e.g. asthma, hay fever.

Why: e.g. Celiac disease may be associated with dermatitis herpetiformis; presence of allergic type conditions such as asthma, hives and hay fever; varicose veins may suggest varicose eczema (patches of dry scaly skin that overlie leg varicose veins); Erythema nodosum may be associated with sarcoidosis, inflammatory bowel disorders (Crohn's disease and ulcerative colitis) and some infections (streptococcal, tuberculosis, leprosy and fungal infections); necrobiosis lipoidica is often associated with diabetes mellitus.

Why: some medications may cause sensitivities such as aspirin, morphine and codeine.

Why: e.g. food allergies, insect allergies, drug allergy, plants (grevillea, poison ivy), rubber, resins, coral, perfumes, dyes, metal salts (nickel, chromate).

Why: e.g. allergies, psoriasis, eczema.

Why: important with respect to allergic contact dermatitis e.g. contact with resins, rubber, latex, dyes.

Why: e.g. a very itchy rash may suggest hives, atopic dermatitis, scabies, skin lice, insect bites, chicken pox, dermatitis herpetiformis; a mild to moderate itchy rash may suggest tinea, psoriasis, drug eruption or lichen simplex.

Why: may suggest chicken pox, exfoliative dermatitis, severe allergic contact dermatitis (e.g. from a strong allergen such as poison ivy); eczema herpeticum.

Why: e.g. itchy, red, dry, scaling, cracked skin. The typical distribution changes as the person grows older. In infants the rash is usually on the cheeks of the face, the folds of the neck and scalp. It may then spread to the limbs and groin. During childhood a drier ad thicker rash develops in front of the elbow, behind the knees and on the hands and feet, which may be dry, itchy, cracked and painful. Rarely does eczema have an adult onset.

Why: e.g. may range from faint redness to severe swelling, symptoms are often worse in area around the eyes, genitals and on hairy skin, symptoms are least on hairless skin such as palms and soles. Allergic contact dermatitis is usually confined to the site of exposure to the allergen.

Why: e.g. red, coin-shaped patches which are crusted, scaly and itchy. Often symmetrical and occurring mainly on the legs but also the buttocks and trunk.

Why: e.g. very itchy dry skin condition that occurs on the legs of elderly people especially in winter and results in a dry "crazy paving" pattern.

Why: e.g. red lesions that enlarge and develop a silvery scale. The commonest sites are the backs of the elbows and knees, then the scalp, sacral areas, genital and nails.

Why: e.g. extremely itchy condition with vesicles (fluid filled blisters less than 1 cm in diameter) mainly over the elbows and knees but may also occur on the trunk, buttocks and shoulders. Associated with Celiac disease.

Why: e.g. leg swelling, darkened skin, inflammation of the skin, possible ulceration on the lower legs - may suggest "varicose eczema" which is characterized by patches of dry scaly skin that overlie leg varicose veins.

Why: e.g. bright red, raised, tender nodules (circumscribed palpable mass on the skin surface, less than 1 cm diameter) on the shins. The nodules may appear on the thighs and the arms also. Adult females are typically affected. May be associated with sarcoidosis, inflammatory bowel disorders, some medications and some infections.

Why: e.g. sharply circumscribed, multicolored (red, yellow, brown) plaques (flat topped palpable mass larger than 1cm diameter) occurring on the front and sides of the lower legs. It is often, but not always associated with diabetes mellitus.